The invention relates to a method for holding a substance in suspension and to a bioreactor for holding a substance in suspension.
The artificial production of tissue material, designated in English as “tissue engineering”, is increasingly gaining in importance in order to produce biological substitutes for damaged tissue or damaged organs. Artificial tissue material can be produced in that cell cultures in vitro are deposited at or in a tissue carrier, also termed a matrix. The tissue carrier consists for example of a synthetic polymer or of a biological material such as collagen. A tissue carrier of this kind is also designated as a “scaffold”. The cells are sown out onto the tissue carrier and begin to multiply if the environmental parameters are physiologically favorable. The tissue carrier can be designed in such a manner that the latter disintegrates with time, so that after a certain time only the tissue part which is formed from the cells is present. The tissue carrier and/or the tissue which is formed on it is designated as “substance” in the following. The conditions which are required for the cell growth are produced in a bioreactor, within which the required oxygen and a nutrient medium are supplied to the substance and within which the substance remains from several days to weeks until the desired size has been reached. The geometrical shape which the artificially produced tissue material assumes during growth is substantially influenced through the measures by means of which the substance is held in the bioreactor.
Thus in the following the term “substance” will be understood to mean both the tissue carrier per se and the tissue carrier with cells deposited on it, or, if the tissue carrier is designed to be decomposable, the artificially produced cell culture or the artificially produced tissue part respectively.